We will study the pre-and post synaptic dynamics function using both electrophysiological and electrochemical techniques. The ability of rats to learn novel motor tasks is dependent on cerebellar norepinephrine. We have demonstrated an age-dependent loss in both motor learning ability and norepinephrine function. Therefore, we will continue to investigate this problem with aged rats and identify specific mechanisms within the cerebellar cortex which contribute to motor learning. A second focus of project 1 will be to investigate the role of alterations in noradrenergic and or cholinergic function in aged-related declines in spatial memory tasks. We will identify the specific noradrenergic receptors which are altered in the hippocampus of aged rats. A new direction for project 1 will be investigation of nicotinic cholinergic receptors in the hippocampus. This aspect of cholingeric receptors are diminished in Alzheimer's disease. The presynaptic characteristics of NE release will also be investigated in Project 1 using in vivo electrochemistry. Potassium evoked release of NE will be examined in terms of the dynamics of release and the diffusion of NE in the rain of old rats. Another new direction for this project will be the development of an electrochemical probe for in vivo measurement of ACh overflow.